Add pollState when setting automatic network selection mode is done.

Fixed to update isManualNetworkSelection in ServiceState when the
network selection mode changes btw manual and automatic.
If there is no change in the network on which the device is camping,
there is no opportunity to update isManualNetworkSelection in
ServiceState, so trigger pollState to update ServiceState once when
the network selection mode is changed.

Bug: 326041360
Test: atest FrameworkTelephonyTests
Change-Id: Iea2e7d246ceb90026289db9539dbce53d1edf964